Oral Cavity

Question 1

What are the boundaries of the oral cavity formed of

Answer 1

Lateral walls - buccinators

Roof - hard and soft palate

Floor - formed by number of muscles, tongue and soft tissue

Question 2

Describe where the oral cavity begins and ends. What forms these parts

Answer 2

Oral cavity begins as oral fissue -> extends posteriorly to the orophargyneal isthmus

Oral fissue - opening to the mouth

Isthmus is an arch formed by soft palate above and upper surface of the tongue below. Anterior and posterior arches form sides of isthmus - formed by palatoglossus (anterior) and palatopharyngeal (posterior)

Question 3

How is the oropharyngeal isthmus closed off from the oral cavity during chewing

Answer 3

Contraction of palatoglossus and palatopharyngeal muscles pulls soft palate down towards back of the tongue to close oropharyngeal isthmus

Question 4

What is found between the palatoglossal and palatopharyngeal arches

Answer 4

Tonsillar fossa - palatine tonsil is found within

Question 5

Where do the salivary ducts drain into the oral cavity

Answer 5

Submandibular drains via Wharton duct - under tongue

Parotid drains via Stensen/parotid duct

Sublingual have many excretory ducts per gland

Question 6

How are the muscles of the tongue divided and what does each division do

Answer 6

Intrinsic - lie within tongue. Run longitudinally, vertically and transversely. Alter shape of tongue

Extrinsic - change position of the tongue. Anchor tonuge to surrounding structures: hyoid and mandible below, styloid process and soft palate above

Question 7

What are the extrinsic muscles of the tongue and which is used to test a CN (which CN)

Answer 7

Genioglossus - protrudes tongue. Used to test hypoglossal nerve (CN XII)

Hypoglossus

Styloglossus

Palatoglossus

Question 8

What is the nerve innervation to the tongue - sensory and motor

Answer 8

Hypoglossal nerve innervates all muscles of tongue except palatoglossus (vagus)

Anterior 2/3 - general sensation by lingual branch of Vc. Chorda tympani fibres supply special sensory

Posterior 1/3 - general sensory glossopharyngeal. Carries both general and special sensory

Question 9

Describe the pharynx

Answer 9

Muscular tube that continues as the oesophagus

Arises from skull base -> descends down to level of C6 where it beocmes oesophagus

Is divided into nasopharynx, oropharynx and laryngopharynx

Is narrowest inferiorly where it becomes the oesophagus

Question 10

What is the nasopharynx

Answer 10

First part of pharynx

Lies superior to soft palate

Nasal cavities open into it through two choanae

C1 lies posteriorly

Orifice of Eustachain tube and pharyngeal tonsil are found

Question 11

What is the oropharynx

Answer 11

Second part of the pharynx

Extends from level of soft palate to superior border of epiglottis

C2 and C3 lie posteriorly

Palatine tonsils lie either side in the tonsillar fossa

Question 12

What is the laryngopharynx

Answer 12

Third part of the pharynx

Extends from epiglottis to the oesophagus at level of the inferior border of cricoid cartilage

Lies immediately behind the larynx - C3-6 lie posteriorly

Piriform recesses are found on each side fo laryngeal inlet - epiglottis diverts materal into piriform recesses to prevent food entering larynx

Question 13

Externally, what do the walls of the pharynx consist of

Answer 13

Walls of pharynx externally consist of circular superior, middle and inferior constrictors

These contract and relax sequentially to propel food into the oesophagus

Posteriorly these muscles form pharyngeal raphe - common midline, tendinous insertion

Question 14

What does the inferior constrictor consist of

Answer 14

Two muscles bellies: thyropharyngeus and cricopharyngeus

This corresponds to where muscles arise from thyroid and cricoid cartilages

Question 15

What is Killian’s dehiscence

Answer 15

Area between the muscle bellies of the inferior constrictor

If there is incoordination of pharynx during swallowing, pressure within pharynx can rise and cause part of pharyngeal mucosa to herniate through Killian’s dehiscence

Forms pharyngeal pouch/diverticulum

Question 16

Internally, what do the walls of the pharynx consist of and what are the names of the muscles

Answer 16

Internally, walls of pharynx consist of three longitudinal muscles that act to shorten and widen the pharynx during swallowing and speaking

Muscles:

• Stylopharyngeus
• Palatopharyngeus
• Salpingopharyngeus - helps open Eustachian tube

Question 17

What do the muscles that form the internal wall of the pharynx do

Answer 17

They directly or indirectly connect to thyroid cartilage -> more larynx up

Help elevate pharynx and larynx during swallowing

Question 18

What is the motor and sensory supply of the pharynx

Answer 18

Motor - vagus supplies muscles of pharynx and soft palate - exception is stylopharyngeus (CN IX)

Sensory:

• Nasopharynx - maxillary branch of trigeminal
• Oropharynx - glossopharyngeal nerve
• Laryngopharynx - vagus

Question 19

What are some complications of adenoiditis (think about what it may obstruct)

Answer 19

May obstruct passage of air from nasal cavities into nasopharynx -> causes mouth breathing and nasal tone to speech

Can block eustachain tube -> lead to otitis media and otitis media with effusion

Question 20

Name some oral cavity pathologies

Answer 20

Sialolithiasis - salivary duct stones

Non-otological causes of otalgia

Peritonsillar abscesses

Cranial nerve probelsm in oral cavity

Tonsillitis

Question 21

Describe sialolithiasis

Answer 21

Stones can form in ducts draining salivary glands causing pain and swelling

Submandibular most commonly affected

Swelling and pain can fluctuate in relation to eating

Infection may occur due to stasis of saliva

Caused by dehydration and reduced salivary flow

Question 22

Why might patients have non-otological causes of otalgia

Answer 22

Nerves supplying sensory innervation to pharynx also supply sensory innervation to ear -> referred pain

Consider non-otological causes of otalgia if present with otalgia and normal ear

Places where referred pain may originate: tongue, oropharynx, cervical spine, oesophagus, nose, sinuses, TMJ

Question 23

What is tonsillitis, what is the most common cause and what are the symptoms

Answer 23

Inflammation of the palatine tonsils

Virus is most common cause but strep throat (e.g. strep pyogenes) is most common bacterial cause

Symptoms: pain, sore throat, pain/difficulty swallowing, bad breath, swollen cervical lymph nodes

Question 24

Why might a patient develop peritonsillar abscesses and what are the symptoms

Answer 24

Can develop due to aerobic or anaerobic bacteria

Can be secondary to poorly/untreated tonsillitis

Pushes uvula off to the side due to tissue around tonsils becomes inflammed

Symptoms: sore throat, bad breath, drooling, difficulty opening mouth, voice changes

Question 25

What do problems with CN IX, X and XII look like in the oral cavity

Answer 25

CN IX and X problems - absent gag reflex, uvula deviated away from lesion, dysphagia, taste impairment in posterior tongue, loss of sensation to oropharynx

CN XII problems - tongue wasting, tongue deviation (points to side of lesion), fasciculations